This invention relates generally to detection and sorting systems. More particularly, the invention is concerned with systems which require detection of a characteristic in a moving object or series of objects.
In a sorting system use is generally made of a detector which is responsive to a selected characteristic and to which each object which is to be sorted is exposed. A decision is made on the suitability of an object by examining the detector output and the object is then accepted or rejected. This approach while being simple suffers from the disadvantage that statistically it is not always accurate. For example the orientation of an object may be such that the presence of a desirable feature is over emphasized or minimized and a wrong decision on the object may therefore be made. Similarly if objects are being sorted on the basis of their radioactivity, radioactive counts obtained from the objects are subject to statistical variations and consequently the classification of an object after exposure to a single detector may be faulty.
The present invention provides a method and means for detecting a characteristic in a moving object or series of objects with improved accuracy and a correspondingly improved method and apparatus for sorting objects according to the degree to which they possess a certain characteristics.